Universal laser power controller in a gas ion laser system

Abstract

A multi-mode/universal laser power controller is disclosed for use in an overall laser system. An associated method is also disclosed. The controller may drive one of at least two different laser tubes which require different particular sets of drive voltages. The power controller includes a first arrangement for selecting first and second modes of operation of the power controller depending on and corresponding to which specific one of the two different laser tubes the power controller is intended to drive and a power conversion arrangement which is designed to operate from one of at least two different AC input voltages and which is responsive to the particular mode selected by the first arrangement such that the power conversion arrangement uses a selected one of the input voltages to produce the particular set of drive voltages to be used to drive the specifically selected laser tube. In one feature, a method is disclosed for starting the gas ion laser tube. In another feature, an arrangement is disclosed for providing an anode current control signal by measuring a sense voltage in the anode lead such that the sensed voltage is not subjected to filament current which circulates in the cathode lead. In yet another feature, the power controller includes a primary ground and switching means electrically connected to the primary ground for use in regulating the flow of anode current.

What is claimed is: 
     
       1. A multi-mode power controller for use in a laser system which may include one of at least two different laser tubes to be driven by different particular sets of drive voltages, said power controller comprising: a) a first arrangement for selecting first and second modes of operation of the power controller depending on and corresponding to which specific one of said two different laser tubes the power controller is intended to drive; and   b) a power conversion arrangement which is designed to operate from one of at least two different AC input voltages and which is responsive to the particular mode selected by said first arrangement such that the power conversion arrangement uses a selected one of the input voltages to produce the particular set of drive voltages to be used to drive the specifically selected laser tube.   
     
     
       2. The power controller of claim 1 including a second arrangement for selecting either approximately 110 volts AC as said input voltage or 220 volts AC as said input voltage. 
     
     
       3. The power controller of claim 1 wherein each AC input voltage may include an actual AC voltage which is above or below an intended AC voltage and said particular sets of drive voltages include certain voltages which are intended to be fixed in value from one set of drive voltages to the next, but which drive voltages vary based upon the actual AC voltage provided and wherein said power conversion arrangement includes means for adjusting the value of said certain voltages towards said intended fixed values based upon the actual AC voltage provided. 
     
     
       4. The power controller of claim 1 wherein said power conversion arrangement is configured to provide particular sets of drive voltages to drive laser tubes having anode to cathode voltages in the range of approximately 70 volts DC to at least 200 volts DC. 
     
     
       5. The power controller of claim 4 wherein said power conversion arrangement is configured to drive a laser tube having an anode to cathode voltage of either 70 VDC, 100 VDC or 200 VDC. 
     
     
       6. The power controller of claim 5 wherein said power conversion arrangement includes means for selecting anode to cathode voltages of either 70 VDC, 100 VDC or 200 VDC. 
     
     
       7. The power controller of claim 1 wherein said power conversion arrangement is configured for applying the set of drive voltages to the specific laser tube being driven in a way which induces less than 3% total harmonic distortion on the AC input being used. 
     
     
       8. In a laser system including a power supply arrangement configured for operating a gas ion laser tube, said power supply arrangement itself including (i) a boost arrangement configured for generating a boost voltage, said boost arrangement requiring a predetermined period of time after startup to build up said boost voltage, (ii) a buck arrangement configured for using said boost voltage to generate and apply an anode voltage to said laser tube to produce an anode current, and (iii) means for generating a tube startup voltage and for applying the startup voltage to the laser tube, a method of starting said tube, said method comprising the steps of: a) starting said boost arrangement so as to begin to build up said boost voltage;   b) applying said startup voltage to the laser tube;   c) waiting for said predetermined period of time as said boost voltage builds up;   d) initiating said buck arrangement such that the buck arrangement begins to generate said anode voltage thereby producing said anode current; and   e) after said anode current reaches a threshold value, removing said startup voltage.   
     
     
       9. In a power supply for use in a gas ion laser system including a laser tube having an anode and a cathode which are powered using an anode lead and a cathode lead, respectively, in electrical connection with said power supply which itself includes means for controlling the level of anode current provided to said laser tube in response to a control signal, said control means being referenced directly to a primary ground in said power supply, a method of generating said control signal, said method comprising the steps of: a) sensing anode current flowing in said anode lead as a detected voltage which detected voltage is floating with respect to said primary ground;   b) producing a feedback current in direct proportion to said detected voltage;   c) using the feedback current in a way which produces a feedback voltage that is referenced to ground; and   d) generating said control signal using said feedback voltage.   
     
     
       10. In a power supply for use in a gas ion laser system including a laser tube having an anode and a cathode which are powered using an anode lead and a cathode lead, respectively, in electrical connection with said power supply which itself includes means for controlling the level of anode current provided to said laser tube in response to a control signal, an arrangement for providing said control signal, said arrangement comprising: a) first means subjected to the anode current present in said anode lead for producing a sense voltage which is directly proportional to the anode current; and   b) second means for using said sense voltage to generate said control signal.   
     
     
       11. The arrangement of claim 10 wherein said first means comprises a shunt resistor located in said anode lead. 
     
     
       12. The arrangement of claim 10 wherein said control means is referenced to a primary ground in said power supply and wherein said second means includes (i) a mirror current generator for producing a sense current which is directly proportional to said sense voltage and (ii) means for converting the sense current into a feedback voltage referenced to said primary ground for use in generating said control signal. 
     
     
       13. In a power supply for use in a gas ion laser system including a laser tube having an anode and a cathode which are powered using an anode lead and a cathode lead, respectively, in electrical connection with said power source, said power source including a primary ground, the improvement comprising: switching means including at least first and second terminals and means for selectively providing a closed state in which the first and second terminals are substantially shorted together and an open state in which a substantial resistance is presented between the first and second terminals, said first terminal being electrically connected directly to said primary ground and said second terminal being electrically connected such that current flows from the cathode lead to the second terminal and, thereafter, through the switching means when the switching means is in its closed position.   
     
     
       14. The improvement according to claim 13 wherein said switching means comprises a MOSFET including a source terminal and a drain terminal such that said source terminal serves as said first terminal and said source terminal serves as said second terminal. 
     
     
       15. In a power supply for use in a gas ion laser system including a laser tube having an anode and a cathode which are powered using an anode lead and a cathode lead, respectively, in electrical connection with said power supply, said power supply including a primary ground, a power regulation arrangement for controlling the level of anode current provided to said laser tube, said arrangement comprising: a) first means subjected to the anode current present in said anode lead for producing a sense voltage which is directly proportional to the anode current;   b) second means for using said sense voltage to selectively generate a control signal; and   c) switching means including an input terminal receiving said control signal and having at least first and second terminals such that when said control signal is present on said input terminal a closed state is provided between the first and second terminals in which the first and second terminals are substantially shorted together and, in the absence of said control signal, an open state is provided in which a substantial resistance is presented between the first and second terminals, said first terminal being electrically connected directly to said primary ground and said second terminal being electrically connected such that current flows from the cathode lead to the second terminal and, thereafter, flows through the switching means when the switching means is in its closed position.   
     
     
       16. The arrangement of claim 15 wherein said first means comprises a shunt resistor through which the anode current passes. 
     
     
       17. The arrangement of claim 15 wherein said switching means comprises a MOSFET.